This invention relates to railroad track working equipment and is particularly concerned with a machine for driving spikes in ties.
In railroad track construction, the rails are laid on tieplates which rest between the tie and the rail. The tieplates are then fastened to the ties by spikes. Generally, two spikes are used for each tieplate, one on each side of the rail. Holes are provided in the tieplate to receive the spikes.
Driving the spikes requires that they be properly aligned with the holes in the tieplate before the driving pressure is applied. This is done with the use of spike holders. Once the spike is aligned, the driver must hit the spike precisely on the head or it will be bent out of shape or improperly driven.
To achieve a high rate of production, the number of misdirected drive strokes must be kept to a minimum. This requires precise alignment of the spike driving mechanism. Early versions of high production spike driving machines used a high impact, hammer-like drive stroke. Because of the high speed of this drive stroke, it was impossible to align after the stroke had been initiated so the only alignment took place while the mechanism was in its fully raised position. This resulted in a high number of miss-hits due to the difficulty of aligning the driver. Later machines used a slower drive stroke. This provided some opportunity for correction of the driver position but still did not permit precise location just before the driver came in contact with the spike.